Apartment add-ons to homes pose problems

The demand for ''second units,'' or granny flats, is growing with a need to create affordable rental housing. The issue being tackled by urban planners is no longer whether or not to legalize ''second units,'' but how to adopt an effective ordinance.

Also known as ''in-law apartments,'' they are additional housing units, either separate from or attached to, an existing single-family home.

In some cases the units are rented out, while in others they are occupied by family members.

The conversion possibilities for ''second units'' are extensive: (1) adding separate cottages in the backyard; (2) converting basements or garages; (3) altering large houses to incorporate a second unit; and (4) constructing a second-story addition.

The problem with them, however, is that they are often created in violation of longstanding building codes and zoning laws which preserve the single-family character of neighborhoods.

Arthur Young of the Bureau of the Census estimates there may be 1.5 million illegal second units nationwide. Most cities are aware of these illegal conversions but rarely go to the expense of abating them.

Moreover, ordinances contain guidelines which discourage homeowners from legalizing the apartments. In Corte Madera, a California community of 3,500 homes, for example, there have been only six applications in the last several years for the creation of second units under the community's ordinance.

In a second-unit workshop sponsored by the Association of Bay Area Governments in Oakland, former Corte Madera city council member Jana Haehl noted the reasons residents have not taken action to either legalize an existing second unit or create a new legal apartment:

* A conditional-use permit is required. This means that all the neighbors are notified and invited to protest the new apartment unit.

* Inspection of both primary and second units will take place. Many residents are reluctant to let a building inspector into their homes because they suspect he may discover fire-code violations or work done without a permit.

* Present ordinances require some means of rent control.

* Property reassessment brings about an additional tax burden.

Mr. Haehl's recommendation is to remove some of the disincentives in current second-unit ordinances.

One way to liberalize ordinances is to permit second units unconditionally in single-family zones, provided they meet all other zoning-ordinance requirements. The switch would eliminate a need for public hearings or extensive fees and would treat requests for permits like any other modification to the home.

To further encourage second-unit conversions, some cities are in the process of relaxing standards on design review, parking, rent control, and minimum lot size.

In addition to the revision of planning and building codes to encourage more legal units, Prof. Martin Gellen of the University of California at Berkeley in his study, Under-Utilization in American Housing, suggests that centers be established to provide technical assistance to interested homeowners and that deferred loans be made available to low-income owners.

Some residents are concerned that liberalizing ordinances would turn their single-family neighborhoods into multiple-family areas and, as a result, property values would drop. The low level of second-unit applications and the typical size limitations, however, appear to suggest that significant increases in neighborhood density are very unlikely.

Despite the kinks that still must be worked out of current second-unit ordinances, the advantages to these accessory apartments are becoming clearer as interest rates remain high and construction costs accelerate faster than income.

Second units, in modifying the existing interior of a home, cost far less to build than starting from scratch on undeveloped land.